Embryonic Green-Light Exposure Modulates Redox Homeostasis, Neuroendocrine Profiles, and the Hypothalamic Proteome in Two Chicken Strains

Embryonic environmental conditions can influence post-hatch physiology in poultry. This study evaluated whether green-light incubation modifies post-hatch redox homeostasis, peripheral endocrine responses, and hypothalamic proteomic remodeling in Roman Pink and Hy-Line Brown chickens. Yolk hormone profiles were screened in 16 breeder strains, revealing clear strain-specific differences in serotonin (5-HT), dopamine (DA), testosterone (TES), and corticosterone (CORT). Roman Pink and Hy-Line Brown chickens were selected for further experimentation, as they showed contrasting yolk endocrine status. A total of 296 eggs from each strain (148 eggs per treatment having four replicates of 37) were incubated under light-emitting diode (LED) green-light or control incubation. Post-hatch antioxidant status, humoral immune response, endocrine indices and hypothalamic proteomes were evaluated. Strain- and age-dependent post-hatch changes in antioxidant status and endocrine profiles were noticed. Green-light incubation enhanced total antioxidant capacity by enhancing total antioxidant capacity (T-AOC), catalase (CAT) and superoxide dismutase (SOD) activity in both strains, and reduction of CORT and TES was observed in Roman Pink chickens (p < 0.05). Proteomic analysis indicated regulation of mitochondrial oxidative phosphorylation, peroxisomal metabolism, antioxidant-related pathways, and monoamine-associated proteins including tryptophan hydroxylase 2 (TPH2), solute carrier family 6 member 4 (SLC6A4), and catechol-O-methyltransferase (COMT). Correlation analyses further linked mitochondrial and antioxidant-related proteins with physiological redox and endocrine indices. These findings suggest that embryonic green-light exposure influences post-hatch antioxidant status, hepatic endocrine profiles, and hypothalamic protein abundance in a strain-dependent manner.